Internal combustion engine with an air inlet valve and a fuel injection valve

ABSTRACT

An air inlet valve and a fuel injection valve cooperate with a common combustion chamber of an internal combustion engine cylinder to supply a mixture of air and fuel thereinto in properly timed relation. The air inlet valve comprises a valve body covering with a valve seat for controlling inlet of air into the combustion chamber and having a hollow valve stem, the fuel injection valve being disposed for operative movement in said stem to inject fuel into the combustion chamber when the inlet valve is opened.

O Unlted States Patent 1151 3,704,694

Gilewski et a1. [45 D 5, 1972 541 INTERNAL COMBUSTION ENGINE 2,072,4372/1937 Wurtele ..123/9o.12 WITH AN AIR INLET VALVE AND A 2,179,27811/1939 Wurte1e.... ..123/32 FUEL INJECTION VALVE 2,280,386 4/1942Dickson ..123/139 [72] Inventors: Heinz Gilewski; Jurgen Wolf, bothFOREIGN PATENTS OR APPLICATIONS of Wolfsburg, Germany 951,603 10/1956Germany ..123/32 [73] Assignee: Volkswagenwerk Aktiengesellschaft,

wolfsburg' Germany Primary Examiner-Laurence M. Goodridge [22] Filed:Jan. 6, 1971 Assistant Examiner-Ronald B. Cox

Attorney-Watson, Cole, Grindle & Watson [21] Appl. No.: 104,319

[57] ABSTRACT [30] Foreign Applicatim Priority Data An air inlet valveand a fuel injection valve cooperate with a common combustion chamber ofan internal 1970 Germany P Q1 @1616 combustion engine cylinder to supplya mixture of air [52] U.S. C1. ..123/32 VN, 123/32 R and fuel thereintoin P p y timed relation The air [51] 1nt.Cl ..F02b 3/00 inlet ValveComprises a Valve y covering with a [58] Field of Search ..123/32 VN vlv seat for controlling inlet of air into the bustion chamber and havinga hollow valve stem, the [56] References Cited fuel injection valvebeing disposed for operative movement in said stem to inject fuel intothe combustion UNITED STATES PATENTS chamber when the inlet valve isopened.

878934 2/ 1908 16 Claims, 8 Drawing Figures 1,638,585 8/1927 1,313,6088/1919 1,602,090 10/1926 2,059,720 11/1936 PATENTEDnEc 5:912

saw u 0F 5 FIG.7

IN VEN TOR PATENTEDHEB i n 3.704.694

SHEET 5 0F 5 IN V EN TOR INTERNAL COMBUSTION ENGINE WITH AN AIR INLETVALVE AND A FUEL INJECTION VALVE This invention relates to an internalcombustion engine of the type which employs an air inlet valve and afuel injection valve, both of which are associated with the combustionchamber of a cylinder and in which the air inlet valve contains a valvebody cooperating with a valve seat and supported on a movable valvestem. The features of the invention can be used both in reciprocatinginternal combustion engines as well as in diesel engines. The inventionis intended primarily for use with motors for motor vehicles, but canalso be used advantageously in other applications, for example, inconnection with stationary engines.

lntemal combustion engines with air inlet valves and fuel injectionvalves have heretofore been known, for example, in a form where separatesuch valves have been provided, whereby the air inlet valve has beendisposed directly on the cylinder head, while the fuel injection isaccomplished in the area of the intake manifold at a location remotefrom the air inlet valve. Such relative spacing of the valves has theeffect of creating a buffer chamber between the place of injection andthe entrance of the intake manifold into the combustion chambers of therespective cylinders and may lead to disturbing uncertainties in regardto the actual time of injection, that is to say, the time at which thefuel actually reaches the respective combustion chambers.

In certain special engines and particularly in diesel engines, it hasbeen known to provide for-a direct injec tion of of fuel into thecombustion chamber under pressure. This measure, however, isdisadvantageous because of the fact that the film of lubricating oil onthe cylinder wall of the engine may be washed away by the injected fuel.

An important object of the present invention is the creation of auniversally usable internal combustion engine, which will avoid thedisadvantages above enumerated of the prior art and which, moreover,will have further advantages, especially in the field of simplifiedconstruction and operation. The internal combustion engine, according tothe invention, is characterized in that the valve stem of the air inletvalve is hollow and the fuel injection valve and passages have beendisposed in it.

In accordance with the invention, therefore, the air inlet valve and thefuel injection valve are combined into a common constructional unit.This offers the advantage that the place of fuel injection and thus thetime of injection are clearly defined. The undesirable washing away oflubricating oils and the repeated local impingement of fuel on certainareas of the cylinder and piston will be avoided, especially when,according to the preferred embodiment of the invention, the valve bodyis disposed inside the combustion chamber and the injection nozzles ofthe fuel injection valve are provided in an area of the valve stemadjacent to the valve body. In this embodiment, therefore, the valvebody, preferably in the form of a valve head, will be disposed withinthe combustion chamber for cooperation with a seat in an internal wallof the cylinder or the cylinder head, and the injection nozzles, asviewed from the combustion chamber, lie outwardly of the combustionchamber beyond the valve body. The outwardly directed surface of thevalve body will be formed to assure a turbulent motion and intermixingof the air and fuel flowing into the combustion chamber. This can beachieved in a relatively simple manner, for example by providinggenerally spirally arranged swirl surfaces or twisted edges on the uppersurface of the valve body, radiating from the valve stem.

The hollow valve stem adjacent to the valve body may be formed withradial ports, between which are disposed angularly spaced sectors of thevalve stem, hereinafter sometimes referred to as braces, by which thevalve stem is fixedly connected to the valve head. With thisarrangement, the inflow of the fuel through the nozzle in the fuelinjection valve is free and unimpeded.

The injection valve may contain a nozzle head inserted in fiuidtightsliding relation in the hollow valve stem and having injection nozzlesand a locking ram, the latter being operatively movable inside saidnozzle head, either to close and isolate the injection nozzles from thefuel supply or to place them in communication with the fuel supply.

Thus, the nozzle head is connected to a valve rod within the valve stem,the valve rod and therefore the head being suitably secured againstaxial movements, as by connection of the valve rod to a distributorshaft on the cylinder head.

The present invention is distinguished by the fact that a pump chamberfor the fuel to be injected as well as a check valve have been disposedbetween the nozzle head with its injection nozzles and the valve rodwithin the valve stem, the arrangement being such that the check valveconnects the pump chamber with the injection nozzles only during thesuction cycle of the engine, and during other operational cyclesconnects it only with the fuel supply. While the injection of a definitequantity of fuel will be assured by the pump chamber, the provision ofthe check valves serves the purpose of preventing delivery of fuel intothe cylinder by interruption of the connection between the fuel supplyon the one hand and the nozzle head on the other.

The pump chamber may be formed within the hollow stem by a radiallyconstricted portion of the nozzle head immediately below its connectionwith the valve rod.

A particularly advantageous feature of the invention is the arrangementof the cam shaft for adjustment both axially in accordance with theposition of the gas control lever and also for angular advance orretardation as may be desirable to adapt to changing loads on theengine. The cams of the cam shaft are formed with cam surfaces which areprofiled both axially and circumferentially. This feature offers thepossibility of varying the time of the fuel injection, both inaccordance with the position of the throttle valve and also inaccordance with the load on the engine.

Additional features and advantages of the invention will be apparentfrom the following detailed description taken in conjunction with theaccompanying drawings, in which:

FIG. 1 presents a diagrammatic sectional view of a portion of areciprocating internal combustion engine including a portion of thecombustion chamber and the intake and fuel injection valves associatedtherewith, the intake and injection valves both being closed.

FIG. 2 is a cross-section on the line II-II of FIG. 1.

FIG. 3 is a view similar to FIG. 1, but with the intake and injectionvalves in their open positions during the suction cycle of thecombustion chamber.

FIG. 4 is a cross-section on the line IV-IV of FIG. 3.

FIG. 5 is a view similar to FIGS. 1 and 3, but with the valves in thepositions which they occupy immediately after conclusion of the suctioncycle.

FIG. 6 is a section on the line VI-VI of FIG. 5.

FIG. 7 is a diagrammatic view,"partly in elevation and partly insection, and including the mechanism for operating the valves; and

FIG. 8 is a fragmentary diagrammatic perspective view of the cam shaftof an engine to which the engine is applied and its associated drivingand adjusting means.

The structure of the preferred embodiment of the invention given by wayof example, will now be explained. The elements of the invention aredesignated in the various figures by the same reference numerals.

The valve arrangement comprises: The valve stem 1, having an end portion2 thereof formed with radially directed ports or openings 2a adjacent tothe valve body 3, which is in the form of a valve head, and whichcooperates with the valve seat 4, which defines an intake port oropening in the cylinder head 5 of the engine. Valve stem 1 is guided forlengthwise movement through a guide sleeve G, affixed to the cylinderhead 5 as in FIG. 7. As is shown in FIGS. 1, 3, 5 and 7, the valve stem1 is hollow and houses therewithin the fuel injection valve, whoseprimary components are the nozzle head 6, the internally threaded upperportion of which is threaded onto and supported by the lower end of thevalve rod 8, the head 6 being formed with a radially constricted orreduced portion or area 7, spaced inwardly from the wall of the tubularstem 1 to form therewith a pump chamber 18 and having radial ports 18aopening from the hollow interior of the nozzle head 6 into the pumpchamber 18. It will be noted that the upper end of the hollow nozzle 6communicates, under the control of the double acting rarn or valve body10, with the fuel passage 19 through the valve rod 8. The double actingvalve body 10 of the check valve is carried by the locking ram 9 which,in turn, is slidably disposed in the nozzle head 6 for movement in anaxial direction.

During operation of the engine, when the injection valve is closed, asin FIG. 1, the locking ram 9 has its lower conical end 11 in engagementwith a mating conically recessed seat 12 of the nozzle head 6, throughwhich seat the fuel injection nozzles 13 and 13a have been provided forthe injection of fuel. When the conical end 11 of the locking ram thusengages the conically recessed seat 12 of the nozzle head, it covers andcloses the injection nozzles 13 and 13a. There may be a suitable numberof such nozzles which are disposed substantially perpendicularly throughthe downwardly directed face of the conical seat 12.

When the locking ram 9 is raised from its seated position shown in FIG.1, to the position shown, for example, in FIG. 3, it uncovers nozzles 13and 13a to place these nozzles in communication with the fuel channels14, 15, 16 and 17, best shown in FIGS. 1 and 2. The result of this isthat, as is shown in FIG. 3, the double acting valve body 10 of thecheck valve will move upwards to close the lower end of the fuel passage19 and thus disrupt or discontinue the communication between the pumpchamber 18 and the fuel line 19. For this purpose, the double actingvalve body 10 is acted upon by two relatively opposed compressionsprings 20 and 20a, the upper spring 20 of which is stronger than thelower spring 200. Thus, the pressure of the fuel in the line 19,together with over-powering pressure of the spring 20 will normally tendto maintain the double acting valve body 10 and the locking ram 9 in theposition shown in FIG. 1 to close the injection nozzles 13 and 13a.However, as soon as the cylindrical pump piston 21, shown in FIG. 1, ismoved downwardly with the surrounding valve stem 1 for a sufficientdistance, it increases the pressure of fuel within the pump chamber 18to an amount sufficient to move the valve body 10 upwardly by pressureon the downwardly directed shoulder of its radial flange or projection23a. The resulting upward movement of valve body 10 carries with it thelocking ram 9 to unseat the end 11 of the locking ram from the conicalvalve seat 12, and to uncover nozzles 13 and 13a. In addition to itsmain portion 10, the double acting valve body has associated therewithan annular member or portion 22 having a larger external diameter thanthe adjacent portion of the valve body 10, so that the cylindricalpiston 2l which moves with the valve stem 1, controls the operation ofthe check valve and thus of the injection valve in the preferredembodiment here illustrated. Piston 21 is fixed to the valve stem 1 foraxial movement therewith relative to the injection valve 6, which issupported from the fixed valve rod 8 by means of the radially ported andradially constricted upper end portion 7 of the nozzle head 6. Themovement of the valve stem 1 and piston 21 is coupled with the operationof the air inlet valve 3.

As indicated in FIG. 3, after uncovering the nozzles 13 and 13a, thefuel flows freely through such nozzles in the form of jets 24 which aredirected diagonally downwardly through the ports 2a of the valve stemand through the intake port of the cylinder defined by the valve seat 4for entrainment in theinflowing air indicated by the arrows 25 in FIG.3.

The radially constricted and ported section 7 of the nozzle head 6 isshown in cross-section in FIG. 4, wherein the ports 18a open radiallyoutwardly through said section 7 into the pump chamber 18.

The mode of operation of the invention is as follows:

When the intake valve 3 is closed, as in FIG. I, the nozzles 13 and 13aare covered by the locking ram 9 which is in its lowered and seatedposition so that no fuel can flow through these nozzles.Correspondingly, the double acting ram 10 is also in its lowest positionand seated against the member 22 to prevent any backflow of fuel fromthe fuel channels 14 to 17 as the result of suction or under-pressureoccurring in the pumping chamber 18.

When the suction cycle of the cylinder is initiated by the downwardmovement of the valve stem 1, together with the valve head 3 andcylindrical piston 21, as shown in FIG. 3, then, in consequence of therelatively high pressure occurring in the pumping chamber 18, theenlarged piston like head or flange 23 of the double acting ram 10 ismoved upwardly by such pressure counter to the action of the spring 20and unseated from member 22 to permit flow of fuel from the pump l06009GI 52 chamber 18 to the fuel channels 14 through 17, and the pressurereliefdmember or valve 22 is moved downwardly by the fuel pressureagainst the action of spring 20a. The precisely defined quantity of fuelcontained in the pumping chamber 18 is delivered through channels 14through 17 to the nozzles and is sprayed outwardly through the nozzles13 and 13a as jets 24, as in FIG. 3, both by the compressive action ofthe cylindrical piston 21 and by the suction within the engine cylinder,the jets of fuel 24 being mixed with the inflowing air 25 by thespirally arranged swirl surfaces 26 to 29, respectively, on the upper orouter face of theintake valve 3.

As soon as the pressure in the pumping chamber 18 is reduced at thecompletion of the suction cycle and the pump chamber 18 has beenemptied, the double acting valve body 10 of the check valve will returnto its starting position as shown in FIG. 5, even prior to the closingof the air inlet valve, or, in other words, before the valve head 3seats against the valve seat 4. Again, therefore, the pumping chamber 18is connected only with the fuel supply line 19, while its connectionwith the fuel channels 14 to 17, inclusive, leading to the nozzles 13and 13a, is interrupted by seating of the valve body 10 on the upper endof the pressure relief valve 22. Thus, the pumping chamber 18 will befilled again with fuel from the fuel passage 19 in readiness for thenext suction cycle.

Since the locking ram 9 will also have returned to its seated position,it will be impossible for any fuel retained in the channels 14 to 17 tobe discharged through the nozzles 13 and 13a, prior to the next cycle ofoperation.

FIG. 7 shows diagrammatically a preferred form of actuating means forthe valve assembly above described. As mentioned above, valve rod 8,defining therewithin the fuel supply channel 19 extends upwardly throughthe upper end of the valve stem 1 and is secured to the cylinder headdistributor shaft 40, which, in turn, contains a channel 41 throughwhich fuel is delivered under pressure into the supply passage 19 in amanner to avoid the formation of bubbles in the fuel.

For driving the valve stem 1 and the cylinder pump piston 21, there isprovided a rocker arm 42 in combination with the valve spring 43 whichis compressed between the retainer attachment 44 fixed on the valve stem1 and the cylinder head 5. The valve spring 43, therefore, resilientlyurges the valve stem 1 and the cylindrical pump piston 21 upwardly.

The rocker arm 42, which is suitably fulcrumed at 45, is oscillatedangularly about its fulcrum by a cam 46 on rotating cam shaft 81.According to the invention, the cam 46 is movable in two directions, i.e. it is movable in the direction of its axis of rotation, as indicatedby the double arrow 47, as determined by the position of the gas leveror throttle, and may be advanced or retarded angularly in its rotationabout its axis, as indicated by the double arrow 48, in accordance withthe load on the engine. The surface of the cam 46, therefore, isprofiled both axially, in the direction of arrows 47 andcircumferentially in the direction of arrow 48, (see FIG. 7) and isoperatively engaged by the cam follower 49 which, in turn, is connectedto the rocker arm 42 at 50 to angularly position the rocker arm inresponse to the angular and axial movements of the cam 46.

The operation of cam 46 may be achieved in simple manner through helicalgears 83 and 84 employed for transmission of rotation from thecrankshaft of the engine to the camshaft 81, as shown diagrammaticallyin FIG. 8, wherein the camshaft 81 is supported for rotation and foraxial shifting movement together with the gear 84 affixed to it. As aresult, the required rotary retardation or advancement of the cam 81, inaccordance with the load imposed on the engine, may be assured throughthe use of a servo motor 85 which is responsive to such loading to shiftthe camshaft 81 accordingly.

More specifically, and as is illustrated in FIG. 8, the crankshaft 80and the camshaft 81 are interconnected by the two helical gears 83 and84. The camshaft 81 is slidable axially in relation to the crankshaft 80as by means of the servo motor 85, which is controlled in response toloading of the engine, as a result of which, because of the helicallyarranged interrneshing teeth of the gears 83 and 84, there is produced arelative angular movement between the said gears which serves torelatively advance or retard the rotary movement of the camshaft 81.

Having thus described our invention, we claim:

1. For use in an internal combustion engine, valve mechanism includingan air intake valve comprising a valve head and an elongated, hollow,cylindrical, axially shiftable valve stem connected to the head forshifting the latter between open and closed position in response toaxial movement of the stem, and a fuel injection valve disposed withinsaid hollow stem, said fuel injection valve comprising:

a nozzle head structure mounted in said stem for axial movement relativethereto, said structure being disposed in spaced relationship relativeto said valve head in a direction axially of the stem to present ahollow space in the stem between the valve head and the structure, therebeing at least one fuel injection port in said air intake valveintercommunicating said hollow space and the area surrounding the airintake valve,

said nozzle head structure comprising a nozzle head element disposedadjacent said space, a fuel inlet element disposed in axially spacedrelationship relative to said head element and means rigidlyinterconnecting said elements to present a fuel metering chamber havinggenerally fixed dimensions in said stem therebetween,

there being at least one injection nozzle passageway extending throughsaid nozzle head element for normally intercommunicating the space andthe chamber and a fuel inlet passageway extending from the fuel inletelement and into the chamber;

rod means connected to said nozzle head structure for holding the samemotionless relative to the stem when the latter is shifted axially;

piston means carried by the valve stem and extending into said chamberfor reducing the volume of the latter when the valve stem is movedaxially relative to the nozzle head structure in a direction to open theair intake valve; and

metering valve mechanism including a double acting valve body mounted insaid chamber for movel06009 0153 It.

ment between an injection nozzle passageway closing position and a fuelinlet passageway closing position, there being pressure responsive meanson the valve body for moving the latter toward its fuel inlet passagewayclosing position in response to an increased pressure in said chamberresulting from a reduction of the volume thereof by virtue of the axialmovement of the stem in said direction to open the air intake valve,whereby a metered quantity of fuel is discharged through the injectionnozzle and said port when the air intake valve is opened.

2. Valve mechanism as set forth in claim 1 wherein is included pressurerelief means disposed in said chamber and operable for increasing thevolume of the latter in response to the development of an excessivepressure therein.

3. Valve mechanism as set forth in claim ll wherein said port extendsthrough the wall of the valve stem adjacent said valve head.

4. Valve mechanism as set forth in claim 3 wherein the surface of thevalve head adjacent said port is characterized by a surface formation inthe form of twisted edges shaped to cause thorough mixing of air andfuel.

5. Valve mechanism as set forth in claim 1 wherein said piston meansincludes a cylindrical piston disposed in surrounding relationship tosaid fuel inlet element and having an end portion extending into saidchamber.

6. Valve mechanism as set forth in claim 5 wherein said injection nozzlepassageway and said fuel inlet passageway are generally axially alignedand said double acting valve body is axially elongated and shiftable inan axial direction.

7. Valve mechanism as set forth in claim 6 wherein said nozzle headelement includes means presenting a central, axially extending recessextending toward and terminating in communication with said injectionnozzle passageway, said double acting valve body including an elongatedextension received in said recess, said body and said recess beingconfigured to present at least one axially extending fuel channeltherebetween normally intercommunicating said injection nozzlepassageway and said chamber.

8. Valve mechanism as set forth in claim 7 wherein is included aplurality of said injection nozzle passageways, the portion of saidrecess adjacent said passageways being defined by wall means having aconical configuration, said nozzle passageways extending from saidadjacent portion of the recess and generally perpendicularly throughsaid wall means.

9. Valve mechanism as set forth in claim 8 wherein the elongatedextension of the double acting valve body is provided with a conicallyconfigured terminus which is complemental in shape to said portion ofthe recess adjacent said nozzle passageways whereby the latter with theend of said fuel passageway which opens into the chamber to prevent fuelfrom entering the chamber.

1 1. Valve mechanism as set forth in claim 10 wherein is included meansfor yieldably biasing said double acting valve body in an axialdirection toward the injection nozzle passageway and away from the endof the fuel inlet passageway, said double acting valve body including anannular abutment adjacent said end element thereof, said abutment beingdisposed generally in a plane perpendicular to the axis of the stem andfacing into said chamber to present said pressure responsive means forforcing said valve body toward the end of the fuel passageway againstthe bias of the yieldable biasing means when the pressure in the chamberis increased beyond a predetermined level.

12. Valve mechanism as set forth in claim 11 wherein is provided meanspresenting an enlarged annular space surrounding said recess andcommunicating with said chamber, there being an annular pressure reliefvalve element disposed in said annular space in surrounding relationshipto said elongated extension and spring means urging said element towardsaid chamber and into sealed contact with said portion of the valvebody, said relief valve element being larger in diameter than saidportion and operable to be shifted into the annular space to increasethe volume of the chamber when the pressure in the latter exceeds apredetermined level.

13. Valve means as set forth in claim] wherein said engine includes acamshaft mounted for both axial and angular movement and a cam lobe onthe camshaft configured to transmit axial movement to a valve stem inoperable connection therewith in response to either axial or angularmovement of the camshaft, said valve stem being in operable connectionwith said lobe.

14. Valve means as set forth in claim 1 wherein said engine includes adistributor shaft, said rod means being connected to the distributorshaft and being held thereby to prevent axial movement of the nozzlehead structure with the valve stem.

15. Valve mechanism as set forth in claim 1 wherein said rod means andsaid fuel inlet element are interconnected, said rod means having anaxial bore therethrough presenting said inlet fuel passageway.

16. Valve mechanism as set forth in claim 4 wherein said surfacecomprises helically inclined surface portions.

1. For use in an internal combustion engine, valve mechanism includingan air intake valve comprising a valve head and an elongated, hollow,cylindrical, axially shiftable valve stem connected to the head forshifting the latter between open and closed position in response toaxial movement of the stem, and a fuel injection valve disposed withinsaid hollow stem, said fuel injection valve comprising: a nozzle headstructure mounted in said stem for axial movement relative thereto, saidstructure being disposed in spaced relationship relative to said valvehead in a direction axially of the stem to present a hollow space in thestem between the valve head and the structure, there being at least onefuel injection port in said air intake valve intercommunicating saidhollow space and the area surrounding the air intake valve, said nozzlehead structure comprising a nozzle head element disposed adjacent saidspace, a fuel inlet element disposed in axially spaced relationshiprelative to said head element and means rigidly interconnecting saidelements to present a fuel metering chamber having generally fixeddimensions in said stem therebetween, there being at least one injectionnozzle passageway extending through said nozzle head element fornormally intercommunicating the space and the chamber and a fuel inletpassageway extending from the fuel inlet element and into the chamber;rod means connected to said nozzle head structure for holding the samemotionless relative to the stem when the latter is shifted axially;piston means carried by the valve stem and extending into said chamberfor reducing the volume of the latter when the valve stem is movedaxially relative to the nozzle head structure in a direction to open theair intake valve; and metering valve mechanism including a double actingvalve body mounted in said chamber for movement between an injectionnozzle passageway closing position and a fuel inlet passageway closingposition, there being pressure responsive means on the valve body formoving the latter toward its fuel inlet passageway closing position inresponse to an increased pressure in said chamber resulting from areduction of the volume thereof by virtue of the axial movement of thestem in said direction to open the air intake valve, whereby a meteredquantity of fuel is discharged through the injection nozzle and saidport when the air intake valve is opened.
 2. Valve mechanism as setforth in claim 1 wherein is included pressure relief means disposed insaid chamber and operable for increasing the volume of the latter inresponse to the development of an excessive pressure therein.
 3. Valvemechanism as set forth in claim 1 wherein said port extends through thewall of the valve stem adjacent said valve head.
 4. Valve mechanism asset forth in claim 3 wherein the surface of the valve head adjacent saidport is characterized by a surface formation in the form of twistededges shaped to cause thorough mixing of air and fuel.
 5. Valvemechanism as set forth in claim 1 wherein said piston means includes acylindrical piston disposed in surrounding relationship to said fuelinlet element and having an end portion extending into said chamber. 6.Valve mechanism as set forth in claim 5 wherein said injection nozzlepassageway and said fuel inlet passageway are generally axially alignedand said double acting valve body is axially elongated and shiftable inan axial direction.
 7. Valve mechanism as set forth in claim 6 whereinsaid nozzle head element includes means presenting a central, axiallyextending recess extending toward and terminating in communication withsaid injection nozzle passageway, said double acting valve bodyincluding an elongated extension received in said recess, said body andsaid recess being configured to present at least one axially extendingfuel channel therebetween normally intercommunicating said injectionnozzle passageway and said chamber.
 8. Valve mechanism as set forth inclaim 7 wherein is included a plurality of said injection nozzlepassageways, the portion of said recess adjacent said passageways beingdefined by wall means having a conical configuration, said nozzlepassageways extending from said adjacent portion of the recess andgenerally perpendicularly through said wall means.
 9. Valve mechanism asset forth in claim 8 wherein the elongated extension of the doubleacting valve body is provided with a conically configured terminus whichis complemental in shape to said portion of the recess adjacent saidnozzle passageways whereby the latter are closed when said conicalterminus iS forced against the wall means defining the conical portionof the recess.
 10. Valve mechanism as set forth in claim 7 wherein saiddouble acting valve body includes a portion at the opposite axial endthereof from said extension which is larger in diameter than the latter,said portion including an end element complementally configured to matewith the end of said fuel passageway which opens into the chamber toprevent fuel from entering the chamber.
 11. Valve mechanism as set forthin claim 10 wherein is included means for yieldably biasing said doubleacting valve body in an axial direction toward the injection nozzlepassageway and away from the end of the fuel inlet passageway, saiddouble acting valve body including an annular abutment adjacent said endelement thereof, said abutment being disposed generally in a planeperpendicular to the axis of the stem and facing into said chamber topresent said pressure responsive means for forcing said valve bodytoward the end of the fuel passageway against the bias of the yieldablebiasing means when the pressure in the chamber is increased beyond apredetermined level.
 12. Valve mechanism as set forth in claim 11wherein is provided means presenting an enlarged annular spacesurrounding said recess and communicating with said chamber, there beingan annular pressure relief valve element disposed in said annular spacein surrounding relationship to said elongated extension and spring meansurging said element toward said chamber and into sealed contact withsaid portion of the valve body, said relief valve element being largerin diameter than said portion and operable to be shifted into theannular space to increase the volume of the chamber when the pressure inthe latter exceeds a predetermined level.
 13. Valve means as set forthin claim 1 wherein said engine includes a camshaft mounted for bothaxial and angular movement and a cam lobe on the camshaft configured totransmit axial movement to a valve stem in operable connection therewithin response to either axial or angular movement of the camshaft, saidvalve stem being in operable connection with said lobe.
 14. Valve meansas set forth in claim 1 wherein said engine includes a distributorshaft, said rod means being connected to the distributor shaft and beingheld thereby to prevent axial movement of the nozzle head structure withthe valve stem.
 15. Valve mechanism as set forth in claim 1 wherein saidrod means and said fuel inlet element are interconnected, said rod meanshaving an axial bore therethrough presenting said inlet fuel passageway.16. Valve mechanism as set forth in claim 4 wherein said surfacecomprises helically inclined surface portions.